Search the Dictionary

ction of the optic axis that objects are most distinctly seen. (b) The line in a doubly refracting crystal, in the direction of which no double refraction occurs. A uniaxial crystal has one such line, a biaxial crystal has two. -- Optical circle (Opt.), a graduated circle used for the measurement of angles in optical…

d circular polarization of light. -- Optically positive, Optically negative. See under Refraction.

ployment of subjective and objective mechanical means to determine the accomodative and refractive states of the eye and the scope of its function in general."

incrustations on the stems of plants, -- formerly supposed to have the quality of uniting fractured bones.

f curves defined by the equation y = axn where n is a positive whole number or a positive fraction. For the cubical parabola n = 3; for the semicubical parabola n = Cubical, and Semicubical. The parabolas have infinite branches, but no rectilineal asymptotes.

er number, quantity, mass, etc., whether actually separate or not; a piece; a fragment; a fraction; a division; a member; a constituent. And kept back part of the price, . . . and brought a certain part and laid it at the apostles'feet. Acts v. 2. Our ideas of extension and number -- do they not contain a secret relati…

on, upon the hypothesis that some of the variables are for the time constant. -- Partial fractions (Alg.), fractions whose sum equals a given fraction. -- Partial tones (Music), the simple tones which in combination form an ordinary tone; the overtones, or harmonics, which, blending with a fundamental tone, cause its…

A highly refractive vitreous composition, variously colored, used in making imitations of precious stones or gems. See Strass.

Obstinate; willful; refractory. [Obs.] -- Per`vi*ca"cious*ly, adv. -- Per`vi*ca"cious*ness, n. [Obs.]

referred for the purpose of determining their relative position in space. -- Plane of refraction or reflection (Opt.), the plane in which lie both the incident ray and the refracted or reflected ray.

t is usually a reflecting plate, or a plate of some crystal, as tourmaline, or a doubly refracting crystal.

tive, and said of metals, bases, and basic radicals. Positive crystals (Opt.), a doubly refracting crystal in which the index of refraction for the extraordinary ray is greater than for the ordinary ray, and the former is refracted nearer to the axis than the latter, as quartz and ice; -- opposed to negative crystal, o…

ysis of the lower extremities; -- so named from Percival Pott, an English surgeon. Pott's fracture, a fracture of the lower end of the fibula, with displacement of the tibia. Dunglison.

onformity to a rule or a standard; definiteness. I have left out the utmost precisions of fractions. Locke.

r sides, and two equal and parallel triangular ends or bases; -- used in experiments on refraction, dispersion, etc.

, one of the single florets, or corollets, in an aggregate or compound flower. -- Proper fraction (Arith.) a fraction in which the numerator is less than the denominator. -- Proper nectary (Bot.), a nectary separate from the petals and other parts of the flower. -- Proper noun (Gram.), a name belonging to an individ…

rs of the spectrum, and formed in the part of the hemisphere opposite to the sun by the refraction and reflection of the sun's rays in drops of falling rain.

n, -- usually measured and designated by the strength of the lens which if added to the refracting media of the eye would cause the rays from the near point to appear as if they came from the far point. -- Range finder (Gunnery), an instrument, or apparatus, variously constructed, for ascertaining the distance of an i…

, below. -- Extraordinary ray (Opt.), that one or two parts of a ray divided by double refraction which does not follow the ordinary law of refraction. -- Ordinary ray (Opt.) that one of the two parts of a ray divided by double refraction which follows the usual or ordinary law of refraction. -- Pencil of rays (Geom…

Kicking back; recalcitrating; hence, showing repugnance or opposition; refractory.